In this short video Omar Suleiman talks about a hadith, where the sahaba told the Prophet (peace and blessings be upon him) that from time to time these unspeakable thoughts occur in their minds. And the Prophet said that that is proper faith, and Allah will reward them. What is the source of that hadith?
The hadith referred to in the video on the unspeakable thoughts is:
عَنْ أَبِي هُرَيْرَةَ قَالَ جَاءَ نَاسٌ مِنْ أَصْحَابِ النَّبِيِّ صلى الله عليه وسلم فَسَأَلُوهُ إِنَّا نَجِدُ فِي أَنْفُسِنَا مَا يَتَعَاظَمُ أَحَدُنَا أَنْ يَتَكَلَّمَ بِهِ. قَالَ: وَقَدْ وَجَدْتُمُوهُ. قَالُوا نَعَمْ. قَالَ: ذَاكَ صَرِيحُ الإِيمَانِ
It is narrated on the authority of Abu Huraira that some people from amongst the Companions of the Apostle (ﷺ) came to him and said: Verily we perceive in our minds that which every one of us considers it too grave to express. He (the Holy Prophet) said: Do you really perceive it? They said: Yes. Upon this, he remarked: That is the faith manifest.
It is an authentic hadith in Sahih Muslim that has another hadith, also in Sahih Muslim, that ocurred on a different occassion but conveys the same concept:
عَنْ عَبْدِ اللَّهِ قَالَ سُئِلَ النَّبِيُّ صلى الله عليه وسلم عَنِ الْوَسْوَسَةِ قَالَ: تِلْكَ مَحْضُ الإِيمَانِ
It is narrated on the authority of 'Abdullah ibn Mas'ud that the Apostle (ﷺ) was asked about evil prompting, to which he replied: "It is pure faith."
In addition, another authentic hadith in Sunan Abi Dawud was mentioned in the video on the same topic:
عَنِ ابْنِ عَبَّاسٍ قَالَ جَاءَ رَجُلٌ إِلَى النَّبِيِّ صلى الله عليه وسلم فَقَالَ يَا رَسُولَ اللَّهِ إِنَّ أَحَدَنَا يَجِدُ فِي نَفْسِهِ - يُعَرِّضُ بِالشَّىْءِ - لأَنْ يَكُونَ حُمَمَةً أَحَبُّ إِلَيْهِ مِنْ أَنْ يَتَكَلَّمَ بِهِ فَقَالَ: اللَّهُ أَكْبَرُ اللَّهُ أَكْبَرُ اللَّهُ أَكْبَرُ الْحَمْدُ لِلَّهِ الَّذِي رَدَّ كَيْدَهُ إِلَى الْوَسْوَسَةِ
Narrated Abdullah ibn Abbas: A man came to the Prophet (ﷺ) and said: "Messenger of Allah! one of us has thoughts of such nature that he would rather be reduced to charcoal than speak about them." He said: "Allah is Most Great, Allah is Most Great, Allah is Most Great. Praise be to Allah Who has reduced the guile of the devil to evil prompting."
However, the part about Allah rewarding those who have waswasa (doubts), it is not part of any of the hadiths quoted. It seems to be the words of the presenter, not a scholarly opinion.